1. Technical Field
This invention is related to the field of internal combustion (IC) engine ignition diagnosis systems. More particularly, it is related to the field of detecting ionization current in the combustion chamber of an IC engine and using the detected ionization signal to monitor ignition parameters and diagnose engine performance.
2. Discussion
The prior art includes a variety of conventional methods for detecting and using ionization current in a combustion chamber of an internal combustion engine. However, each of the various conventional systems suffers from a great variety of deficiencies. For example, prior art ionization current detection circuits are generally too slow and generate a current signal with low signal-to-noise ratio.
Typically, the primary coil of an ignition system is charged close to a desired amount of energy as a function of engine operational conditions such as the local mixture air to fuel ratio, pressure, temperature, and engine gas recirculation concentration. Since the breakdown voltage and spark duration at the discharge moment can be different from cycle to cycle, it is desirable to monitor some of these parameters.